Chemicals play an important role in our quality of life, thus it is important to characterize the toxicity of new chemicals so that harmful agents can be highlighted prior to public exposure. The micronucleus (MN) assay is the most widely used system or evaluating a chemical's potential to cause chromosomal damage. This research project will broaden the database of genotoxins analyzed by flow cytometry (FCM), assessing whether rat peripheral blood (after acute or subchronic treatment) is an appropriate compartment for detecting damage caused by genotoxic compounds. Since rat bone marrow is currently accepted by regulatory agencies worldwide, a major line of investigation is to further develop reliable methods for preparing bone marrow samples for FCM analysis. A significant in te rest for automating the rat peripheral blood assay is that the spleen of this species behaves similarly to that of humans. Therefore, this work is extremely important towards our long-term goal of analyzing human blood for the presence of MN. When we are able to measure MN in human blood, it might be possible to determine the genotoxic effects of accidental human exposure and even biomonitor patients receiving chemotherapeutic treatments. PROPOSED COMMERCIAL APPLICATION: Litron, together with the Stratagene Corporation, is developing micronucleus kits for rat peripheral blood and bone marrow. The kits will be in two formats: the first allows researchers to send blood samples to Litron for MN analysis (microFlow kits)to analyze for MN, and the second allows researchers to analyze for MN in-house (micro FlowPlus kits). The pharmaceutical community has responded enthusiastically and has asked for the development of rat kits specifically for their in-house use in addition to the kits, we expect our genetic toxicology contract testing to increase as this advanced technology is refined and brought to the marketplace.